The present invention relates generally to the delivery of a beneficial agent to a patient or into a system for later delivery to a patient. More specifically, the present invention relates to an improved drug delivery system.
For many applications, drugs can be mixed with a diluent before being delivered, for example, intravenously to a patient. The diluent can be, for example, a dextrose solution, a saline solution, or even water. To this end, many drugs are supplied in powdered form and packaged in glass vials. Other drugs, such as some chemotherapy drugs, are packaged in glass vials in a liquid state.
Powdered drugs can be reconstituted by utilizing a syringe to inject liquid into a vial for mixing; the syringe eventually withdrawing the mixed solution from the vial. When a drug must be diluted before delivery to a patient, the drug is often injected into a container of diluent after it is reconstituted; a container can be connected to an administration set for delivery to the patient.
Drugs may be packaged separate from the diluent for various reasons. One of the most important reasons is that many drugs do not retain their chemical and physical stability when mixed with a diluent and thus cannot be stored for any substantial period of time. Also, drugs are often packaged separately from the diluent because many companies that manufacture drugs are not engaged in the business of providing medical fluids and containers for intravenous delivery, and vice versa.
Therefore, doctors, nurses, pharmacists, or other medical personnel must mix the drug and diluent. This presents a number of problems. The reconstitution procedure is time consuming and requires aseptic techniques. The operator must provide the proper diluent and a syringe before beginning. The reconstitution procedure should be performed under preferably sterile conditions. This procedure requires the operator to be more cautious, thereby consuming more time. Additionally, sterile conditions are often hard to maintain. In some instances, a laminar flow hood may be required under which the reconstitution procedure is performed.
A further concern is that some drugs, such as chemotherapy drugs, are toxic. Exposure of the operator to the drugs during reconstitution can be dangerous, especially if the operator works with such drugs on a daily basis and is repeatedly exposed to them.
Although after a drug is reconstituted and withdrawn into a syringe barrel, the drug can, in some instances, be injected immediately into a patient. More typically, however, the reconstituted drug is injected from the syringe into a larger container of solution for connection to an intravenous administration set. A larger container of solution may be necessary because often the reconstituted drug in the syringe is at such a concentration as to cause local toxicity in the veins of a patient near the injection site where the needle pierces the skin. This can create severe vein irritation which can be harmful.
Additionally, even though the proper dose of medication may be in the syringe, immediate injection into the patient's blood stream can create a condition of systemic toxicity wherein the level of drug concentration in the patient's entire blood system is dangerously high. Yet another reason for not making an injection from the syringe directly into the patient is that such an injection creates an additional injection site into the patient; this can be painful for the patient and provides another opportunity for infection.
For these reasons, the reconstituted drug is more typically injected into a diluent container.
A number of drug delivery systems are known. In one delivery system that is currently used, a drug contained in a vial in a solid state is reconstituted with a predetermined volume of diluent using a needle and syringe. The vial containing the drug and solution is then mated onto an intravenous administration set. The drug is delivered to a patient as diluent flows through the vial to the patient carrying with it the dissolved drug.
In another IV drug delivery system, the drug solution is packaged in flexible plastic containers. Some drugs packaged in this manner may be stored at room temperature and the drug is delivered by connecting the container to an intravenous administration set. Some drugs packaged in this manner may be stored in a frozen state in order to improve drug stability. In these cases, the drug solution must be thawed and then connected to an intravenous administration set for delivery to the patient.
Another system requires drugs to be contained in a special vial. An activated vial is then mated to a special container. The vial stopper is removed and the drug is transferred to the container by flushing the vial with the diluent in the container. The drug is delivered by connecting the container with the dissolved drug to an intravenous administration set.
Drugs can also be delivered intravenously via a syringe pump. Briefly, a dose of reconstituted drug solution is withdrawn by a syringe. The drug solution in the syringe is then refrigerated or frozen until use. The drug solution is brought to room temperature and infused into a patient via a syringe pump.
There are some disadvantages with some of the above systems and procedures. One of the disadvantages is drug waste. Due to chemical and physical instability, once a solid drug is reconstituted with diluent (or a frozen formulation is thawed), it cannot be stored for any substantial amount of time. Therefore, if the drug solution is not administered to the patient within a given period of time, the drug must be discarded. Drug waste can be a very costly expense to a hospital pharmacy.
Some of the current procedures for intravenous administration are labor intensive. As previously noted, reconstitution of a drug with a needle and syringe is time consuming and requires an aseptic environment. Likewise, exposure of the operator to the drug may be dangerous, especially if the operator works with the drug on a daily basis. Of course, needle sticks may expose healthcare professionals to hazardous diseases and infections.
A further disadvantage of some of the above procedures is that they require a secondary IV administration set for delivery of the drug. The secondary set can be cumbersome for both the patient and the clinician. Elimination of the secondary set (along with the needle and syringe) may also reduce solid waste and disposal costs.
U.S. Pat. No. 4,850,978 discloses a drug delivery system for delivering drugs to patients and/or reconstitution of a drug. The system includes a cartridge for introducing a beneficial agent into a fluid conduit for delivery of the agent to a patient. The cartridge includes a rigid hollow tube and an agent containing chamber slidably mounted at least partially within the hollow tube. In a first, pre-use position, the chamber extends farther from the hollow tube than it does in a second position. A cannula is mounted to the hollow tube extending opposite the chamber. When the chamber is in the second position, the cannula pierces the closure means creating a flow path.
U.S. Pat. No. 4,804,366 also discloses a drug delivery system including an adapter having an improved flow path means providing both an inlet and an outlet to the agent containing chamber of a cartridge. The cartridge and adapter permit a single opening through the injection sites at opposite ends of the flow path means, while still permitting simultaneous flow both into and out of the chamber. An adapter and a cartridge is provided, including a rigid cannula with an inlet and an outlet and the shell substantially coaxial with and spaced from the cannula intermediate of the cannula inlet and the cannula outlet so that the shell of the cannula defines a channel therebetween. Both the cannula inlet and the cannula outlet are adaptable to form a single piercing opening in a resilient injection site associated with the cartridge.